Gemstones are commonly classified according to various properties, including weight, color and clarity, properties which greatly affect the value of the gemstone. An expert gemologist is usually required to evaluate these properties in order to determine the value of the gemstone and also to identify and distinguish one particular gemstone from all other gemstones. A need therefore exists for a method and apparatus to identify gemstones, enabling even a non-expert to quickly and positively identify any particular gemstone and to distinguish it from others.
A number of methods have been proposed in the past for identifying gemstones, particularly diamonds. Among these known methods are those based on: reflection techniques, as illustrated in U.S. Pat. Nos. 3,740,142 and 3,947,120; geometric scattering techniques, as illustrated in U.S. Pat. No. 4,012,141; Raman refraction techniques, as illustrated in U.S. Pat. No. 4,799,786; ion implantation techniques, as illustrated in U.S. Pat. Nos. 4,200,506 and 4,316,385; laser micro-engraving techniques, as illustrated in U.S. Pat. No. 4,467,172 and Israel Patent No. 64274; and x-ray techniques, as illustrated in U.S. Pat. No. 4,125,770. However, none of these known techniques has yet found widespread use, primarily because of one or more of the following drawbacks: the high cost and cumbersome procedures required for identifying the diamonds; the lack of reproducibility enabling the same identification results to be obtained using various types of identification apparatus and working conditions; and/or the inability of identifying the diamond while held in a setting.